1. Field
The present disclosure relates generally to aircraft and, in particular, to a method and apparatus for presenting information during flight of an aircraft. Still more particularly, the present disclosure relates to a method and apparatus for presenting information for vertical situation awareness that facilitates energy management in an aircraft.
2. Background
Different types of aircraft may fly close to or follow the terrain to perform different types of operations. For example, agricultural aircraft, such as crop dusters, fly at low altitudes over fields to apply pesticides to crops. Some types of passenger and freight aircraft fly close mountainous terrain to deliver passengers and/or cargo to high-elevation airports. Fire fighting air tankers fly close to the terrain to drop water or fire retardant onto or around a fire. Most helicopters fly near terrain throughout their flights.
Military aircraft may fly close to the terrain to drop cargo and paratroops or to avoid detection. The military aircraft may fly within a valley, behind a ridge, or close to some other terrain in a manner that may mask the military aircraft's signature in the ground clutter.
Some aircraft may use terrain following systems. A terrain following system is a guidance system that allows an aircraft to fly safely close to the ground. Further, with the terrain following system, the aircraft may fly safely over terrain, such as valleys or mountains. This type of system may allow an aircraft to fly at night or with no visibility.
Terrain following systems have been used in various military aircraft, such as bombers, fighters, and airlift aircraft. These terrain following systems offer an operator of an aircraft cues to steer the aircraft so as to maintain a desired height above the terrain. Terrain following systems use a display to provide these cues to the operator of the aircraft. These cues may be, for example, graphical indicators, text in windows, and/or other suitable types of cues.
Although a terrain following system may be used for different types of operations, these systems are expensive and require a greater amount of pilot training and practice than desired.
Other aircraft may not include a terrain following system that is designed to guide the pilot to maintain a substantially constant terrain clearance. Instead, these aircraft may have a warning system that is designed to prevent an accidental approach to terrain between takeoff and landing of an aircraft. These types of systems, however, may not be helpful in aiding a pilot intentionally flying close to the ground after takeoff and before landing.
Without a terrain following system, an aircraft may be grounded at night or in low visibility conditions. These conditions include, for example, rain, snow, and fog. Further, without a terrain following system, an aircraft may not be able to fly close enough to the terrain to perform certain types of operations. As one example, fire fighting air tankers are typically grounded at night.
Therefore, it would be advantageous to have a method and apparatus that takes into account one or more of the issues discussed above, as well as possibly other issues.